This invention relates to a direct injection engines and more particularly to an improved direct fuel injection system for an outboard motor.
As is well known, in all fields of engine design there is an increasing emphasis on obtaining more effective emission control, better fuel economy and, at the same time, continued high or higher power output. This trend has resulted in the substitution of fuel injection systems for carburetors as the engine charge former. In order to obtain still further improvements, direct fuel injection systems are being considered. These systems inject fuel directly into the combustion chamber and thus have significant potential advantages.
With outboard motors, two cycle engines are frequently employed because of their compact nature and their high specific output. There is, however, a concern about emission from such engines. Therefore, in order to obtain the advantages of the two cycle engine, steps must be taken to insure that the combustion is clean so as to avoid the emission problems normally associated with such engines. Direct fuel injection systems are quite useful in achieving this goal.
However, there is one running condition in a two cycle engine that presents significant problems in conjunction with direct cylinder injection because of the more frequent firing impulses of such engines. This is under low speed, and low load conditions. Under these conditions, the time during which fuel is injected is relatively short, and the high pressure of the fuel injection, causes the fuel to be maintain in a liquid state in the combustion chamber during the short time period. As a result, uneven and incomplete combustion may result.
It is, therefore, a principle object of this invention to provide an improved fuel injection system for two cycle engines wherein fuel vaporization under low speed, low load conditions can be improved.
It is a further object of this invention to provide an improved fuel injection system for a two cycle engine that improves the vaporization of the fuel under low speed, low load conditions.